Quality inspection and defect analysis starting for semiconductor wafers, including layers, nanostructures up to the complete electronic devices are crucial for improvements of the fabrication technology, based on correlation of device properties with the different technological processes.
The talk demonstrates new capabilities of X-ray imaging techniques with conventional and synchrotron radiation sources for detailed quality inspection concerning structural perfection. It covers real space imaging of microstructures and reciprocal space imaging of nanostructures employed to characterize grown-in and process-induced defects as well as stresses.
Considering real space imaging, it includes results for different materials (SiC, GaAs, InP, GaPO4, GaN and ultrathin silicon) and devices (wafers, thin layers up to completely mounted opto-electronic devices under operation) as well as different fabrication technologies. Examples are: surface damage in thick and ultra-thin silicon wafers, μm-resolved lattice misorientation and dislocation density maps, μm-resolved imaging of GaN layers fabricated by epitaxial lateral overgrowth, degradation in semiconductor laser devices.
Regarding reciprocal space imaging, it overviews high-resolution X-ray scattering techniques for the characterization of periodic nanostructures (e.g. gratings, etched quantum wires and quantum dots, self assembled patterning in strained superlattices).
Examples are: the evolution of residual lattice strain in buried patterned structures during of planar growth, patterning and embedding, periodic interface strain in ultra-thin twist bonded samples, interface morphology, lateral correlation and vertical replication properties in the case of strain-driven self-assembled patterning.